Me, I can't wait to try and, most likely, buy one of these. I had an Air 11" that I sold to a customer that desperately needed one when hers failed and she was going out of town the next morning. Instead of buying a new 11" I went ahead and got a rMPB 13". I have never owned the MacBook Pro and I wanted to try it out and especially use the retina screen. I can say that I love, love, love this screen! But, it has just been way too bulky for me after the 11" Air. I know it's only an extra 1.25 pounds or so more, but I do notice it. I carry it with me everywhere I go, all day long. So a 2 pound MacBook with the same basic footprint as my old Air 11" would be ideal for me.
Yes the single port is a pain... maybe. But I'm sure of a few things: One, USB sticks with USB-C connectors will soon follow (especially since Windows laptops will be adopting USB-C as well) and I am also pretty sure there will be USB-C to ethernet adapter. I do use my TB to ethernet fairly frequently when doing router setups for customers. Otherwise the $80.00 Apple adapter will work, but with yet another dongle for ethernet. Dongles aren't ideal, I know, but I have had one in my laptop bag since the original 2008 Air (which I purchased, with the 64GB SSD--damn that was pricey!) and it only had the single USB port with no ethernet or DVD.
My only concern is the keyboard. I like to write when not doing computer consulting and the keyboard is pretty important to me, so I will definitely need to test it out a bit in store before committing to it. (I wonder if they'd let me install Scrivener on it

)
So, overall, my reaction to the announcement today was very positive. I think this is the perfect tiny, portable laptop for my needs! And my color preference is Space Gray.